While working on bug 945, it was noted that MapScript's prepareImage (SWIG and
PHP) could not easily be made to support non-square pixels. This is a low
priority, but I'm filing this as an enhancement bug so that we don't forget.
Here is what I had written in bug 945:
>
> Frank: I was not sure how to handle the MS_NONSQUARE thing inside
> msPrepareImage() since it requires that the caller should call
> msMapRestoreRealExtent() when he's done. With scripts calling
> $map->prepareimage() there is no way to guarantee that this would happen. To
> resolve the issue quickly, I simply added a allow_nonsquare boolean which is
> set to MS_FALSE from MapScript, and is set to MS_TRUE when called from
> msDrawMap().
> Could you please review what I've done and tell us if it would be possible to
> allow mapscript to call prepareimage with nonsquare pixels and get rid of my
> allow_nonsquare hack?